Automatic optical inspection system and method

ABSTRACT

A system comprising automatic apparatus for automatic optical inspection (AOI), verification and correction of defects in an article, and a processor operative to select between AOI, verification and correction for performing on the article.

FIELD OF THE INVENTION

[0001] The present invention relates generally to automatic opticalinspection (AOI) systems, and particularly to a system and method forautomatic optical inspection, verification and correction.

BACKGROUND OF THE INVENTION

[0002] Automatic optical inspection (AOI) systems are well known for theinspection of printed circuit boards (PCBs), flat panel displays (FPDs)and the like. AOI systems may be used to inspect various aspects andfeatures of such articles during manufacture or assembly thereof, suchas but not limited to, conductor integrity (breaks, continuity,cracking, etc.) and dimensions, insulator or substrate integrity anddimensions, hole size and placement, via size and placement, conductorpitch, line widths and lengths, artwork features, paste, componentplacement, solder joint defects and so forth.

[0003] After AOI, the article may typically be conveyed to averification station for verifying whether defects discovered duringinspection are real defects. If defects are verified as being realdefects, the article may then pass on to a correction station forcorrecting those defects which are correctable (not all defects can becorrected). In the prior art, the verification station and thecorrection station comprise a unit which is located separately from theAOI unit.

SUMMARY OF THE INVENTION

[0004] The present invention seeks to provide a system and method forautomatic optical inspection, verification and correction, whichprovides the possibility of performing inspection, verification andcorrection at one integrated station. This may significantly improvethroughput of AOI systems, provide more flexibility in the manufacturingprocess and diminish or eliminate bottlenecks in the manufacturing flow.

[0005] There is thus provided in accordance with an embodiment of theinvention an integrated system comprising automatic apparatus forautomatic optical inspection (AOI), verification and correction ofdefects in an article, and a controller operative to transfer an articleto be inspected between an AOI location and a verification andcorrection location. Preferably, AOI and verification and correction areperformed simultaneously on two separate articles.

[0006] In accordance with an embodiment of the invention the automaticapparatus comprises a first station comprising an AOI device and asecond station comprising a device operative to perform at least one ofverification and correction of defects in the article.

[0007] Further in accordance with an embodiment of the invention theautomatic apparatus comprises a first station comprising an AOI device,a second station comprising a verification device operative to verifydefects in the article, and a third station comprising a correctiondevice operative to correct defects in the article.

[0008] Still further in accordance with an embodiment of the invention aconveyor is provided for conveying an article between the first andsecond (and third) stations.

[0009] Still further in accordance with an embodiment of the invention,AOI comprises an image acquisition assembly including a plurality ofilluminators and a plurality of sensors generally extending across theentire width of an article to be inspected, such that an article to beinspected may be inspected by a single non-interrupted pass past theimage acquisition assembly in a first direction and then removed fromthe AOI by transporting the inspected article in a second directiongenerally opposite to the first direction.

[0010] There is also provided in accordance with an embodiment of theinvention a system for the automatic optical inspection (AOI) ofarticles comprising an illumination and image acquisition subsystem, afirst support surface operative during a first time interval to supporta first article to be inspected and to transport the first article pastthe image acquisition subsystem in single uninterrupted pass to acquirean image thereof, and a second support surface operative during thefirst time interval to receive a second article to be inspected at alocation away from the image acquisition subsystem.

[0011] Further in accordance with an embodiment of the invention, thesecond surface is operative during a second time interval to support thesecond article and to transport the second article past the imageacquisition subsystem in single uninterrupted pass to acquire an imagethereof, and the first support surface is operative during the secondtime interval to enable the first article to be removed therefrom and toreceive a third article to be inspected at a location away from theimage acquisition subsystem.

[0012] Still further in accordance with an embodiment of the invention,the illumination and image acquisition subsystem is arranged along anaxis extending generally perpendicularly to an axis of transport of thefirst and second support surfaces.

[0013] There is also provided in accordance with an embodiment of theinvention a method for manufacturing printed circuit boards comprisingproviding automatic apparatus for automatic optical inspection (AOI),verification and correction of defects in an article, performing AOI ona first printed circuit board substrate, and generally simultaneously toperforming verification and correction of suspected defects, previouslyfound by AOI, on a second printed circuit board substrate.

[0014] In accordance with an embodiment of the invention the methodfurther comprises performing another manufacturing step after performingat least one of AOI, verification and correction on the article.

[0015] Further in accordance with an embodiment of the invention themethod further comprises diverting the article to another workstationwhile continuing to perform at least one of AOI, verification andcorrection on the article.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The present invention will be understood and appreciated morefully from the following detailed description taken in conjunction withthe drawings in which:

[0017]FIG. 1 is a simplified pictorial illustration of a system forautomatic optical inspection, verification and correction of articles,constructed and operative in accordance with an embodiment of thepresent invention;

[0018] FIGS. 2A-2I are simplified block diagrams illustrating operationof the system of FIG. 1; and

[0019]FIG. 3 is a simplified flowchart of a method for manufacturingprinted circuit boards in accordance with an embodiment of the presentinvention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0020] Reference is now made to FIG. 1, which illustrates an integratedsystem for automatic optical inspection, defect verification andcorrection of one or more articles 10, constructed and operative inaccordance with an embodiment of the present invention. Articles 10 maycomprise, without limitation, electrical circuits such as printedcircuit boards (PCBs), flat panel displays (FPDs), chip interconnectpackaging (ICPs) and the like.

[0021] The system may comprise, for example, automatic apparatus 12having a chassis 14 defining an inspection location 16 whereat possibledefects in article 10 may be identified, for example by means ofautomatic optical inspection (AOI), and a defect verification andcorrection location 18 whereat the possible defects in article 10 may beevaluated as being real or false defects, and corrected, as needed.

[0022] In the embodiment seen in FIG. 1, automatic apparatus 12comprises an AOI device 20 at inspection location 16, and a verificationdevice including an imaging functionality, designated 22, configured toenable the correction of at least some defects, for example by providinga sufficient working distance between an article 11 and the imagingfunctionality such that a defect can be corrected manually such as byscraping away extraneous copper, at defect verification and correctionlocation 18.

[0023] AOI device 20 is operative to inspect a first article 10 to findpossible defects therein, some of which may be real defects and some ofwhich may be false defects. Verification device 22 is operative toprovide at least one of the following functionalities with respect to aninspected article 11 that has been inspected by AOI device 20: acquiringand displaying an image 23 of a possible defect in inspected article 11such that an operator may determine whether a possible defect is in facta real defect or a false defect, and enabling the operator to correct acorrectable real defect; automatically verifying whether a possibledefect found in article 11 is a correctable real defect, anon-correctable real defect or a false defect, for example by analysisof relatively high resolution image acquired by verification device 22;correcting correctable real defects in article 11; and discardingarticles 11 that have non-correctable real defects. Typical examples ofcorrectable real defects include, for example and without limitation,conductors having various protrusions some of which may result shortcircuits, copper splashes and the like. Examples of non-correctable realdefects may include, for example and without limitation, certain missingfeatures, and conductors having a severe nick, a non-localized improperwidth, breaks along conductors and the like.

[0024] In accordance with an embodiment of the invention, a correctionfunctionality associated with verification device 22 is performedmanually by an operator, or optionally automatically.

[0025] In accordance with an embodiment of the invention, verificationdevice 22 is operative such that the imaging functionality displays animage 23 of a defect which is used by an operator to quickly identifyfalse defects before removal of an inspected article from automaticapparatus 12. Additionally, the imaging functionality may be used by anoperator while correcting inspected article 11 before removal fromautomatic apparatus 12.

[0026] In accordance with an embodiment of the invention, a suitablecomputer image processor may provide an automatic false defect filteringfunctionality. Articles 11 having non-correctable real defects may bediscarded. Articles 11 having correctable real defects may be correctedbefore removal from automated apparatus 12 or passed on to a separatecorrection station along with an indication of each of the correctablereal defects in the article. The locations of false defects arediscarded such that only correctable real defects need be considered ata correction station.

[0027] In accordance with an embodiment of the present invention,verification device 22 is configured such that correction may beperformed at verification and correction location 18. Thus in accordancewith an embodiment of the invention, verification device 22 ispositioned at a sufficient distance from article 11 such that anoperator may access article 11 to perform defect correction whilesimultaneously viewing an image 23 of a portion of article 11 beingcorrected. Optionally, an automated functionality, designated defectcorrector 24, is provided to automatically correct at least some defectsin article 11. A typical defect that may be corrected is excess coppersuch as at a copper splash 26 in a printed circuit board, shown in image23.

[0028] AOI device 20 typically comprises illumination and imageacquisition apparatus (not shown), such as but not limited to,back-lighting and/or top-lighting apparatus, for illuminating article 10during inspection thereof. Article 10 may be inspected with incoherentor coherent light, for example. A preferred embodiment of illuminationapparatus suitable for use in AOI device 20 is described in copendingU.S. patent application Ser. No. 09/719,728 entitled “Illuminator forInspecting Substantially Flat Surfaced”, filed Dec. 13, 2000 as anational phase application of PCT/IL98/00285 filed Jun. 16, 1998, thedisclosure of which is incorporated by reference in its entirety.

[0029] AOI device 20 may further comprise image acquisition apparatus28, such as but not limited to, at least one CCD (charge coupled device)array. In the embodiment seen in FIG. 1, three side-by-side imageacquisition apparatuses 28, each associated with a CCD or CMOS basedimager, are provided such that as an article 10 is transported past theimage apparatuses 28, for example in the direction of arrow 30, severalimage swaths (in the example shown three, each associated with acorresponding image acquisition apparatus 28) of article 10 are acquiredsimultaneously. In this manner, an image of substantially the full widthof article 10 may be acquired from a single uninterrupted pass ofarticle 10 by AOI device 20.

[0030] Different features on article 10 may reflect the illuminatedlight at different intensities. For example, conductors (typicallycopper lines) may reflect the light at a higher intensity than theduller substrate. Thus, the features (e.g., conductors and substrate)may be recognized by an intensity of their reflected light.

[0031] In accordance with an embodiment of the invention, a computerimage processor 21, in operational communication with AOI device mayoutput a report indicating suspected defects in article 10. The computerimage processor 21 may include, for example, hardware image processingcomponents as well as software image processing programs running on oneor more computer workstations.

[0032] Examples of an AOI device 20 that may be adapted for use in asystem operating according to an embodiment of the present inventioninclude, without limitation, InSpire-9000™, SK-75™, and InFinex™ seriesof automatic optical inspection systems, commercially available fromOrbotech Ltd., Yavne, Israel. These systems may be used to inspect PCBsubstrates having features and components, such as without limitation,complex fine lines or ball grid arrays (BGAs).

[0033] The acquisition of images of possible defects in article 11, suchas those found by AOI device 20, may be carried out at defectverification and correction location 18 by various devices, such as butnot limited to, an autofocus video camera, configured for example as anautofocus video microscope 39 as generally described in copending U.S.patent application Ser. No. 09/570,972 entitled “Microscope InspectionSystem”, filed Jun. 15, 2000, the disclosure of which is incorporated byreference in its entirety. Video microscope 39 may be spaced from anitem on article 11, e.g., an electrical circuit, located at defectverification and correction location 18 by a distance which enablesphysical access to the electrical circuit for correction thereof.

[0034] In accordance with an embodiment of the present invention, thedefect verification and/or correction functionality of defect verifier22 is generally operative on an article 11 simultaneously to theinspection of defects in article 10 by AOI device 20 at inspectionlocation 16. Thus, in the embodiment seen in FIG. 1, a first conveyor(not shown) is provided for conveying an article, such as article 10, ona first support surface (or table, the terms being used interchangeably)44 between the various stations. A second conveyor (not shown) may alsobe provided for conveying an article, such as article 11, on a secondsupport surface (or table, the terms being used interchangeably) 46between the various stations. The first and second support conveyors incombination with the first and second support surfaces may also beconsidered as positioners operative to selectably position articles atone of the stations 16 and 18. In accordance with an embodiment of theinvention, in order to accommodate simultaneous inspecting of article 10at inspection location 16 and verification of article 11 at verificationand correction station 18, the respective conveying paths of article 10and article 11 are non-identical.

[0035] Thus, in accordance with an embodiment of the present invention,a first support table 44 supporting article 10 is transported in a firstconveying plane. A second support table 46 supporting article 11 istransported in the first conveying plane at inspection station 20,however to and from inspection station 20 the second support table 46 isat least partially in a second conveying plane generally parallel tofirst conveying plane.

[0036] Reference is now made to FIGS. 2A-2I which are schematic sideview diagrams illustrating the operation of an integrated system forinspection, verification and correction of articles in accordance withan embodiment of the present invention. Each of FIGS. 2A-2Ischematically show a chassis 114, an inspection location 116, a defectverification and correction location 118, an AOI device 120, averification device 122, a first support table 144, and a second supporttable 146. The first support table 144 and second support table 146support, respectively, articles to be inspected during inspection andsubsequent verification and correction.

[0037] In FIG. 2A, a first article to be inspected, designated 150, issupported by support table 144 and is shown being transported in thedirection of arrow 160 during automated optical inspection by AOI device120. Generally during the time interval required by AOI device toautomatically optically inspect first article 150 for defects, a secondarticle 152 is supported by second support table 146 at verificationlocation 118 while verification device 122 is operative to move, asindicated by arrows 162, to locations of suspected defects. Verificationdevice 122 is operative to acquire an image of suspected defects (notshown), which typically are displayed to an operator. It is noted thatthe performance of a verification functionality at verification location118 is optional. In some embodiments of the invention, verificationlocation 118 is used solely for loading and offloading articles from oneof the support tables 144 and 146 during the time interval used toinspect an article loaded on the other support table, without performinga verification or correction functionality thereat.

[0038] As seen in FIG. 2B, upon the completion of automated opticalinspection by AOI device, or upon verification and/or correction of allsuspected defects in second article 152 by verifier 122, the secondarticle 152, which has been both inspected and defects therein at leastpartially verified, has been removed from the second support table (andis not shown in FIG. 2B) and a third article 154 (seen in FIG. 2C) isplaced on second support table 146. The first support table 144, whichbears a now automatically optically inspected first article 150 istransported toward verification and correction location 118 in thedirection of arrow 162.

[0039] Next, as seen in FIG. 2C, the first support table 144, whichremains disposed at a first level, continues to be transported in thedirection of arrow 162. The second support table 146, now bearing thirdarticle 154, drops down, as indicated by arrow 164, to a second leveldisposed below the level of first support table 144, and is transportedtoward inspection location 116 in the direction indicated by arrow 166.

[0040] As seen in FIG. 2D, once second support table 146 clears thefirst support table 144, but generally before reaching inspectionlocation 116, it is lifted up as indicated by arrow 166 to a levelrequired by AOI device 120 to conduct automated optical inspection.

[0041] As seen in FIGS. 2E and 2F respectively, once first support table144 reaches verification and correction location 118 and once secondsupport table 146 reaches AOI location 116, the third article 154 isautomatically inspected for suspected defects with AOI device 120 whilegenerally simultaneously suspected defects on first article 150 areverified and corrected.

[0042] As seen in FIGS. 2G and 2H, once the verification and correctionof selected suspected defects on first article 150 is completed, thefirst article 150 is removed from first support table 144 and replacedby a fourth article 156 (FIG. 2H). The first support table 144 is thentransported in the direction of arrow 170 to inspection location 116.Once the automated optical inspection of third article 154 is completed,second support table 146 is dropped down to a level below first supporttable 144, as indicated by arrow 172, to clear first support table 144,and is transported away from inspection location 116 in the directionindicated by arrow 174.

[0043] Completion of the cycle is seen in FIG. 2I, wherein secondsupport table 146 is raised to a level suitable for verification andcorrection of suspected defects at verification location 118, asindicated by arrow 176. Generally simultaneously to the verification andcorrection of suspected defects on third article 154, first supporttable 144 is transported past AOI device 120 at inspection location 118,in the direction of arrow 170, to inspect fourth article 156 forsuspected defects.

[0044] It is noted that in accordance with an embodiment of theinvention, the relative time intervals for inspection and forverification and correction are mutually interdependent and may beadjusted, for example to accommodate inspection process constraints.Thus in accordance with an embodiment of the invention, the verificationand correction may be made time dependent on the time interval requiredto inspect an article for defects at inspection location 116. In such aconfiguration, only those suspected defects that can be verified andcorrected during a time interval required to perform AOI are handled. Ifnon verified suspected defects remain following the completion of AOI,then an article one which some suspected defects have been verified andother have not been verified is passed on to an offline verification andcorrection station where any remaining suspected defects are thenverified. It is appreciated that in this mode of operation, the load ata stand alone verification and correction station is substantiallyreduced, although it may not be entirely eliminated.

[0045] Alternatively, the integrated system may be configured to bedependent on the time interval required to verify and correct allsuspected defects on an article. In such a mode of operation, should thetime interval required to verify and correct defects and to place a newarticle on a support table exceed the time interval required to inspectan article for defects at inspection location 116, then the returntransport of an inspected article from inspection location 116 toverification location 120 may be delayed. Thus, this mode of operationmay be slower than a mode of operation by which operation of theintegrated system is constrained by AOI, however each article handled bythe system is inspected, verified and corrected thereby eliminating theneed for a stand-alone verification and correction station.

[0046] Reference is now made additionally to FIG. 3, which illustrates amethod for manufacturing printed circuit boards using an integratedsystem for automatic optical inspection, verification and correction ofarticles, in accordance with an embodiment of the present invention.

[0047] A controller 280 (FIG. 1) may be in communication with first andsecond locations 16 and 18 and tables 44 and 46, and may control theflow of operation of the system. Processor 280 may select between whichof the operations—AOI, verification and correction—are to provide aconstraint for completion of inspection, verification and correction ofan article 10, namely. whether articles offloaded from the system are tobe partially or fully verified and corrected.

[0048] In accordance with an embodiment of the present invention, aportion of an electrical circuit pattern is deposited on a substrate,such as a printed circuit board substrate. Typically substrates areprepared in a batch, and each of the substrates in the batch is providedwith the same portion of an electrical circuit pattern.

[0049] Each substrate in a batch of substrates is provided serially toan integrated inspection, verification and correction system such assystem 12 (FIG. 1), whereat a substrate is transported to an inspectionlocation and automatically optically inspected to ascertain the presenceand respective locations of anomalies suspected of being defects. Inaccordance with an embodiment of the invention, during at least part ofthe time that a first substrate is being automatically opticallyinspected, a new substrate is loaded onto the integrated system.

[0050] After completion of automatic optical inspection of a substrate,an automatically optically inspected substrate is transferred to adefect verification and correction location located on the integratedsystem where its suspected defects are verified as being real defects orare determined to be false defects, and correctable real defects arecorrected. In accordance with an embodiment of the invention,verification and correction of suspected defects on an inspectedsubstrate is performed generally simultaneously with the inspection of anew substrate.

[0051] If at least some of the suspected defects have not been eitherverified or corrected, the substrate is passed on to a stand aloneverification and correction station, for example a VRS-4 verificationstation available from Orbotech Ltd. of Yavne, Israel, where suspecteddefects on the substrate are finally verified and, as needed, corrected.Substrates having uncorrectable defects are discarded. It is appreciatedthat a significantly reduced quantity of defects reach the stand aloneverification and correction station, as compared with conventionalinspection, verification and correction methods.

[0052] Once suspected defects are all verified and corrected thesubstrate is removed from the integrated system. If all of the suspecteddefects have been verified and corrected, then the substrate may becombined with other substrates, and additional printed circuit boardprocessing steps, such as application of a solder mask, may be performedto produce a completed printed circuit board.

[0053] It will be appreciated by person skilled in the art that thepresent invention is not limited by what has been particularly shown anddescribed herein above. Rather the scope of the present invention isdefined only by the claims that follow:

What is claimed is:
 1. A system comprising: integrated automaticapparatus for automatic optical inspection (AOI), verification andcorrection of defects in an article; and a controller operative toselect between AOI, verification and correction for performing on thearticle.
 2. The system according to claim 1, wherein said integratedautomatic apparatus comprises a first location comprising an AOI deviceand a second location comprising a device operative to perform at leastone of verification and correction of defects in the article.
 3. Thesystem according to claim 2, further comprising a conveyor for conveyingan article between said first and second stations.
 4. The systemaccording to claim 1, wherein said integrated AOI, verification andcorrection apparatus is operative to perform AOI on a first article andgenerally simultaneously perform one of verification and correction on asecond article.
 5. The system according to claim 4, wherein a time,interval for performing verification and correction of suspected defectson a first article is constrained by a time required to perform AOI on asecond article.
 6. The system according to claim 5, wherein articlesremoved from said system that include non-verified suspected defects areprovided to a stand alone verification and correction station, andwherein said verification and correction station is operative to providea verification and correction functionality with respect to saidnon-verified suspected defects.
 7. The system according to claim 5,wherein articles removed from said system that include non-correctedsuspected defects are provided to a stand alone verification andcorrection station, and wherein said verification and correction stationis operative to provide a verification and correction functionality withrespect to said non-corrected suspected defects.
 8. A method formanufacture of printed circuit boards comprising: forming a portion ofan electrical circuit on a substrate; providing integrated automaticapparatus for automatic optical inspection (AOI), verification andcorrection of defects in said substrate; and selecting between AOI,verification and correction for performing on the substrate.
 9. Themethod according to claim 8, further comprising performing AOI on thesubstrate at an inspection location on said integrated automaticapparatus, and verifying on said integrated automatic apparatus anysuspected defects found during AOI.
 10. The method according to claim 9,further comprising correcting on said integrated automatic apparatus anydefects that have been found during AOI.
 11. The method according toclaim 9, further comprising correcting on said integrated automaticapparatus any real defects that have been verified.
 12. The methodaccording to claim 8, further comprising performing at an inspectionlocation AOI on the substrate, and correcting any defects found duringAOI.
 13. The method according to claim 8, further comprising performinganother manufacturing step after performing at least AOI and correctionon the substrate.
 14. The method according to claim 8, furthercomprising performing on said integrated system AOI on a first substrateand generally simultaneously performing on said integrated system atleast one of verification and correction on a second substrate.
 15. Anintegrated inspection, defect verification and correction system forelectrical circuits comprising: a chassis defining an inspectionlocation and a defect verification and correction location; and anelectrical circuit positioner operative to automatically position anelectrical circuit initially at said inspection location and thereafterat said defect verification and correction location.
 16. An integratedinspection, defect verification and correction system for electricalcircuits according to claim 15, further comprising an optical inspectionassembly located at said inspection location and a video camera locatedat said defect verification and correction location.
 17. An integratedinspection, defect verification and correction system for electricalcircuits according to claim 16 and wherein said video camera comprises avideo microscope.
 18. An integrated inspection, defect verification andcorrection system for electrical circuits according to claim 17, whereinsaid video microscope is spaced from an electrical circuit located atsaid defect verification and correction location by a distance whichenables physical access to said electrical circuit for correctionthereof.
 19. An integrated inspection, defect verification andcorrection system for electrical circuits according to claim 15, whereinsaid electrical circuit positioner comprises at least first and secondelectrical circuit supports, said electrical circuit positioner beingoperative to position said first electrical circuit support at saidinspection location while said second electrical circuit support ispositioned at said defect verification and correction location andthereafter to position said second electrical circuit support at saidinspection location while said first electrical circuit support ispositioned at said defect verification and correction location.
 20. Anintegrated inspection, defect verification and correction system forelectrical circuits according to claim 16, wherein said opticalinspection assembly is static and is operative to inspect an electricalcircuit as said electrical circuit is translated relative thereto andsaid video camera is movable and operable to verify an electricalcircuit as said electrical circuit is static at said defect verificationand correction location.
 21. An integrated inspection and defectverification system for electrical circuits comprising: a chassisdefining an inspection location and a defect verification location; anelectrical circuit positioner operative automatically to position anelectrical circuit initially at said inspection location and thereafterat said defect verification location; an optical inspection assemblylocated at said inspection location and a defect verification assemblylocated at said defect verification location; and an operational modeselector operative to enable operation of said optical inspectionassembly and said defect verification assembly to be selectablycoordinated in time in at least two different modes of operationincluding: a first mode wherein the required time of operation of theoptical inspection assembly governs the maximum duration of operation ofthe defect verification assembly; and a second mode wherein the requiredtime of operation of the defect verification assembly governs themaximum duration of operation of the defect verification assembly.
 22. Asystem for the automatic optical inspection of electrical circuitscomprising: an illumination and image acquisition subsystem; a firstsupport surface operative during a first time interval to support afirst article to be inspected and to transport said first article pastsaid image acquisition subsystem in single uninterrupted pass to acquirean image thereof; and a second support surface operative during saidfirst time interval to receive a second article to be inspected at alocation away from said image acquisition subsystem.
 23. The systemclaimed in claim 21 and wherein: said second surface is operative duringa second time interval to support said second article and to transportsaid second article past said image acquisition subsystem in singleuninterrupted pass to acquire an image thereof; and said first supportsurface is operative during said second time interval to enable saidfirst article to be removed therefrom and to receive a third article tobe inspected at a location away from said image acquisition subsystem.24. The system claimed in claim 22 and wherein: said first and saidsecond support surfaces are transported generally along an axis oftransport; and said illumination and image acquisition subsystem isarranged along an axis extending generally perpendicularly to said axisof transport.